The invention relates to a surgical instrument and particularly an instrument for extracapsular cataract surgery.
With the advent of extracapsular cataract surgery, various methods have been advocated for anterior capsulectomy. These include non-invasive, manual and mechanical techniques. To date, no instrument has been developed for use with mechanical techniques in which a cutting blade or hook is inserted for cutting the anterior capsule. Vitrectomy instruments now in use are not suitable because the cutting mechanism is recessed within a hollow tube and cannot reach the capsule. The present invention is concerned with an instrument particularly useful in mechanical techniques.
One of the potential problems with mechanical techniques is the possibiliity inadvertent engagement of Descemet's Membrane or the iris of the eye.
The present invention relates to the first practical mechanical device in which the cutting blade extends beyond the end of a hollow tube. Moreover, the possibility of inadvertent engagement of Descemet's Membrane or the iris is substantially reduced by mounting a rotating blade in a hollow tube displaced radially from the axis of the hollow tube. The length of the tip distance of the displacement and circumference of the hollow tube are chosen so that, when the blade is rotated 180.degree. from the direction of displacement, the hooked cutting tip is within the region of extension of the tube so that the tip is not readily exposed to these eye parts during incision. After incision, the tip is rotated to be aligned along the direction of displacement for cutting. The blade is coupled to a suitable drive controlled by surgeon in a conventional way.
Other objects and purposes of the invention will be clear from the following detailed description of the drawings.